Silicone is soft and malleable, helping the heart to integrate better with tissue and blood as it is pumped through the body. The 3D printing technique allowed the researchers to make a complex inner structure while still keeping the heart as one single piece. This enables the heart to work as a whole without separate parts that may not fit together perfectly.

While this is just a prototype, the ventricles are able to fill and deflate, imitating the pumping action of a real heart. This heart would not actually be used for implantation, as it would not last for more than half an hour, or a few thousand beats. Researchers still have a hard task ahead of them to make a heart with similar materials and a comparable design that could eventually be used for humans.